An alternative to producing long fiber thermoplastic (LFT) composites with molding pellets or glass mat thermoplastic (GMT) materials is being touted by Composite Products, Inc. (CPI; Winona, MN) as being more cost-effective in providing high-temperature stiffness for components. According to the company, adding 40% glass reinforcement to polypropylene homopolymer raises the heat distortion by 50%; adding the same amount of glass reinforcement to nylon 6 raises its heat distortion temperature by 16%.

But in order to achieve that, the company claims, the molder has a choice: using prefabricated glass/resin pellets or using CPI's patented direct feed thermoplastic (DFT) process. The direct approach, skipping the pellet manufacturing, is said to save the molder about 40% (e.g., for a 40% glass-reinforced polypropylene, the pellet material cost is said to be $1.40/lb. versus $1.00/lb. for the DFT material).

Briefly, the DFT process employs a proprietary extruder design that gently mixes the fiber/resin melt such that the reinforcing fibers aren't damaged so that they maintain a high degree of their initial length in the compounded thermoplastic composite.

One cited application of a 40% glass-filled polypropylene that's made with the DFT process is an under hood front end assembly that is used by Volvo to replace a metal part (the high resistance to heat distortion is said to be a reason why the composite can be used in this application).

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